The present invention relates to a disposable diaper for absorption and containment of body fluids.
Conventional disposable diapers generally comprise a liquid-permeable topsheet made of nonwoven fabric, a liquid-impermeable backsheet made of plastic film and a liquid-absorbent core disposed between these sheets. The topsheet and the backsheet are bonded to each other at portions thereof extending outwardly beyond transversely and longitudinally opposite edges of the core so as to form leg-surrounding flaps and a waist-surrounding flap, respectively. In such diapers, a pair of hydrophobic nonwoven fabrics are attached to an upper surface of the topsheet at the leg-surrounding flaps and elastic members are secured to these nonwoven fabrics along the inner free edges of the leg-surrounding flaps so that these inner free edges may rise on an inner surface of the diaper in order to avoid sideway leakage of body fluids possibly occurring around the legs of a wearer.
With such diapers, body fluids discharged onto the topsheet are absorbed through the topsheet into the core and at the same time laterally spread through the topsheet into the leg-surrounding flaps, possibly causing sideway leakage and giving a wearer an uncomfortable wet feeling. While such sideway leakage, as well as wet feeling, can be alleviated by attaching the hydrophobic nonwoven fabrics to an inner surface of the respective flaps, the amount of body fluids having spread into the hydrophilic topsheet underlying the hydrophobic nonwoven fabric soon exudes on the surfaces of the respective hydrophobic nonwoven fabrics and possibly increases the wet feeling.
Therefore, it is an object of the present invention to provide a disposable diaper having a pair of side flaps which improve the effect of preventing sideway leakage of body fluids.
According to the present invention, there is provided a disposable diaper comprising a topsheet, a backsheet and an absorbent core disposed therebetween. The topsheet comprises a central sheet covering the core and a pair of side sheets lying at transversely opposite sides of the central sheet and extending longitudinally of the diaper together with the backsheet. The central sheet has transversely opposite side edges and longitudinally opposite end edges extending outwardly from a periphery of the core, the side and end edges being bonded to the backsheet. Each side sheet has a proximal zone, an inner zone extending inwardly from the proximal zone and having a distal edge opposed to the proximal zone, and an outer zone extending outwardly from the proximal zone. The proximal zone is bonded to the backsheet without an overlapping side edge of the central zone but in side-by-side relationship with the side edge. The outer zone is bonded to the remaining zone of the backsheet lying outside the proximal zone to form a first side flap. The inner zone extends above the central sheet to form a second side flap and is bonded at longitudinally opposite ends of the inner zone to the central sheet. The first side flap is provided adjacent an outer side edge thereof with an elastic member in an elastically contractible condition. The second side flap is provided along the distal edge of the inner zone with an elastic member in an elastically contractible condition.
The inventive diaper, as described hereinabove, allows a side edge of the central sheet and the proximal portion of the side sheet to be brought into contact with or separated from each other without overlapping each other. In consequence, body fluids are effectively prevented by the side edge of the central sheet from further spreading, i.e., the body fluids cannot spread beyond the proximal zone of the side sheet to the leg-surrounding flap.
Even if the side edge of the central sheet and the proximal zone of the side sheet are separated from each other, as mentioned above, and the location of the applied adhesive is exposed between the side edge of the central zone and the proximal portion, i.e., the inner zone of the side sheet, the second side flap extending above the exposed zone prevents said exposed zone from contacting a wearer""s skin.
Furthermore, where the side edge of the central sheet and the proximal portion of the side sheet are separated from each other, the first side flap curves or stands up more easily along the separated zone defined between the side edge and the proximal zone under the contractible force of the elastic member associated with the first side flap, because the separated zone is more flexible than the remaining zone of the first side flap. Accordingly, the first side flap provides a close contact with a wearer""s skin along the associated zone thereof with the elastic member.